From a lore perspective, DU has several centuries of technology advancement over real-life, plus whatever was done by the AI on the journey to Alioth. Currently weapons systems are VERY far behind in proportion to the other technology present in DU (Warp Drives, Pocket-Dimension-Based Storage, Teleportation, Respawning by using alternate-realities of the avatar, etc.) We have all of this, but current weaponry consists of lock-and-fire elements with less range than their real-life counterparts.
IMO space-faring ships should not use voxels as armor, as the weapons fielded by Noveans in space should theoretically be able to atomize anything they touch.
The railgun is an example of a real-life weapon capable of punching through just about anything. One (or five) fielded in space would easily turn a borg cube into a block of swiss cheese just from shear ballistics alone, not including whatever exotic properties a railgun made with 2500s tech would have. Lasers, not limited by atmosphere, would be able to melt anything the beam touches. Also turning your borg cube into swiss cheese.
Because of this, I believe that shields should be the only practical form of structural defense in space. Your objective in constructing a combat ship would be to maximize shield health and efficiency while balancing power distribution between the shield and your armament, because once the shield is depleted, you and your ship are done.
This would eliminate the borg-cube constructions from a practical perspective, but would still allow diversity in how you design your ships, because weapons are able to easily destroy it without a shield no matter how much material you slap on the core.
For atmospheric engagement, armor would be more effective due to atmospheric properties negating the use of railguns and lasers, as laser energy dissipates and railguns are damaged from the munition being heated by the atmosphere. This would limit armament to cannons and missiles, both of which would do substantial damage but not enough to disable a ship quickly.
This gives armor a purpose, protecting bases and atmospheric ships, but eliminate the practical use of it in space.
In order to stop borg cubes from being the imminent ships in atmosphere, NQ would need to make aerodynamics more of a thing, right now if you slap enough engines on a ship it will fly, but if you make them very hard to maneuver, they would be outclassed by more aerodynamic ships.
